1 /*
2 * Copyright (c) 2003, 2019, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "classfile/systemDictionary.hpp"
27 #include "memory/allocation.hpp"
28 #include "memory/heapInspection.hpp"
29 #include "memory/oopFactory.hpp"
30 #include "memory/resourceArea.hpp"
31 #include "oops/instanceKlass.hpp"
32 #include "oops/objArrayKlass.hpp"
33 #include "oops/objArrayOop.inline.hpp"
34 #include "oops/oop.inline.hpp"
35 #include "prims/jvmtiRawMonitor.hpp"
36 #include "runtime/atomic.hpp"
37 #include "runtime/handles.inline.hpp"
38 #include "runtime/init.hpp"
39 #include "runtime/objectMonitor.inline.hpp"
40 #include "runtime/thread.inline.hpp"
41 #include "runtime/threadSMR.inline.hpp"
42 #include "runtime/vframe.hpp"
43 #include "runtime/vmThread.hpp"
44 #include "runtime/vmOperations.hpp"
45 #include "services/threadService.hpp"
46
47 // TODO: we need to define a naming convention for perf counters
48 // to distinguish counters for:
49 // - standard JSR174 use
50 // - Hotspot extension (public and committed)
51 // - Hotspot extension (private/internal and uncommitted)
52
53 // Default is disabled.
54 bool ThreadService::_thread_monitoring_contention_enabled = false;
55 bool ThreadService::_thread_cpu_time_enabled = false;
56 bool ThreadService::_thread_allocated_memory_enabled = false;
57
58 PerfCounter* ThreadService::_total_threads_count = NULL;
59 PerfVariable* ThreadService::_live_threads_count = NULL;
60 PerfVariable* ThreadService::_peak_threads_count = NULL;
61 PerfVariable* ThreadService::_daemon_threads_count = NULL;
62 volatile int ThreadService::_atomic_threads_count = 0;
63 volatile int ThreadService::_atomic_daemon_threads_count = 0;
64
65 ThreadDumpResult* ThreadService::_threaddump_list = NULL;
66
67 static const int INITIAL_ARRAY_SIZE = 10;
68
69 void ThreadService::init() {
70 EXCEPTION_MARK;
71
72 // These counters are for java.lang.management API support.
73 // They are created even if -XX:-UsePerfData is set and in
74 // that case, they will be allocated on C heap.
75
76 _total_threads_count =
77 PerfDataManager::create_counter(JAVA_THREADS, "started",
78 PerfData::U_Events, CHECK);
79
80 _live_threads_count =
81 PerfDataManager::create_variable(JAVA_THREADS, "live",
82 PerfData::U_None, CHECK);
83
84 _peak_threads_count =
85 PerfDataManager::create_variable(JAVA_THREADS, "livePeak",
86 PerfData::U_None, CHECK);
87
88 _daemon_threads_count =
89 PerfDataManager::create_variable(JAVA_THREADS, "daemon",
90 PerfData::U_None, CHECK);
91
92 if (os::is_thread_cpu_time_supported()) {
93 _thread_cpu_time_enabled = true;
94 }
95
96 _thread_allocated_memory_enabled = true; // Always on, so enable it
97 }
98
99 void ThreadService::reset_peak_thread_count() {
100 // Acquire the lock to update the peak thread count
101 // to synchronize with thread addition and removal.
102 MutexLocker mu(Threads_lock);
103 _peak_threads_count->set_value(get_live_thread_count());
104 }
105
106 static bool is_hidden_thread(JavaThread *thread) {
107 // hide VM internal or JVMTI agent threads
108 return thread->is_hidden_from_external_view() || thread->is_jvmti_agent_thread();
109 }
110
111 void ThreadService::add_thread(JavaThread* thread, bool daemon) {
112 assert(Threads_lock->owned_by_self(), "must have threads lock");
113
114 // Do not count hidden threads
115 if (is_hidden_thread(thread)) {
116 return;
117 }
118
119 _total_threads_count->inc();
120 _live_threads_count->inc();
121 Atomic::inc(&_atomic_threads_count);
122 int count = _atomic_threads_count;
123
124 if (count > _peak_threads_count->get_value()) {
125 _peak_threads_count->set_value(count);
126 }
127
128 if (daemon) {
129 _daemon_threads_count->inc();
130 Atomic::inc(&_atomic_daemon_threads_count);
131 }
132 }
133
134 void ThreadService::decrement_thread_counts(JavaThread* jt, bool daemon) {
135 Atomic::dec(&_atomic_threads_count);
136
137 if (daemon) {
138 Atomic::dec(&_atomic_daemon_threads_count);
139 }
140 }
141
142 void ThreadService::remove_thread(JavaThread* thread, bool daemon) {
143 assert(Threads_lock->owned_by_self(), "must have threads lock");
144
145 // Do not count hidden threads
146 if (is_hidden_thread(thread)) {
147 return;
148 }
149
150 assert(!thread->is_terminated(), "must not be terminated");
151 if (!thread->is_exiting()) {
152 // JavaThread::exit() skipped calling current_thread_exiting()
153 decrement_thread_counts(thread, daemon);
154 }
155
156 int daemon_count = _atomic_daemon_threads_count;
157 int count = _atomic_threads_count;
158
159 // Counts are incremented at the same time, but atomic counts are
160 // decremented earlier than perf counts.
161 assert(_live_threads_count->get_value() > count,
162 "thread count mismatch %d : %d",
163 (int)_live_threads_count->get_value(), count);
164
165 _live_threads_count->dec(1);
166 if (daemon) {
167 assert(_daemon_threads_count->get_value() > daemon_count,
168 "thread count mismatch %d : %d",
169 (int)_daemon_threads_count->get_value(), daemon_count);
170
171 _daemon_threads_count->dec(1);
172 }
173
174 // Counts are incremented at the same time, but atomic counts are
175 // decremented earlier than perf counts.
176 assert(_daemon_threads_count->get_value() >= daemon_count,
177 "thread count mismatch %d : %d",
178 (int)_daemon_threads_count->get_value(), daemon_count);
179 assert(_live_threads_count->get_value() >= count,
180 "thread count mismatch %d : %d",
181 (int)_live_threads_count->get_value(), count);
182 assert(_live_threads_count->get_value() > 0 ||
183 (_live_threads_count->get_value() == 0 && count == 0 &&
184 _daemon_threads_count->get_value() == 0 && daemon_count == 0),
185 "thread counts should reach 0 at the same time, live %d,%d daemon %d,%d",
186 (int)_live_threads_count->get_value(), count,
187 (int)_daemon_threads_count->get_value(), daemon_count);
188 assert(_daemon_threads_count->get_value() > 0 ||
189 (_daemon_threads_count->get_value() == 0 && daemon_count == 0),
190 "thread counts should reach 0 at the same time, daemon %d,%d",
191 (int)_daemon_threads_count->get_value(), daemon_count);
192 }
193
194 void ThreadService::current_thread_exiting(JavaThread* jt, bool daemon) {
195 // Do not count hidden threads
196 if (is_hidden_thread(jt)) {
197 return;
198 }
199
200 assert(jt == JavaThread::current(), "Called by current thread");
201 assert(!jt->is_terminated() && jt->is_exiting(), "must be exiting");
202
203 decrement_thread_counts(jt, daemon);
204 }
205
206 // FIXME: JVMTI should call this function
207 Handle ThreadService::get_current_contended_monitor(JavaThread* thread) {
208 assert(thread != NULL, "should be non-NULL");
209 debug_only(Thread::check_for_dangling_thread_pointer(thread);)
210
211 // This function can be called on a target JavaThread that is not
212 // the caller and we are not at a safepoint. This ObjectMonitorHandle
213 // keeps the ObjectMonitor from being async deflated so the object
214 // reference we fetch remains non-NULL.
215 ObjectMonitorHandle omh;
216 ObjectMonitor *wait_obj = thread->current_waiting_monitor(&omh);
217
218 oop obj = NULL;
219 if (wait_obj != NULL) {
220 // thread is doing an Object.wait() call
221 obj = (oop) wait_obj->object();
222 assert(obj != NULL, "Object.wait() should have an object");
223 } else {
224 ObjectMonitor *enter_obj = thread->current_pending_monitor(&omh);
225 if (enter_obj != NULL) {
226 // thread is trying to enter() an ObjectMonitor.
227 obj = (oop) enter_obj->object();
228 assert(obj != NULL, "ObjectMonitor should have an associated object!");
229 }
230 }
231
232 Handle h(Thread::current(), obj);
233 return h;
234 }
235
236 bool ThreadService::set_thread_monitoring_contention(bool flag) {
237 MutexLocker m(Management_lock);
238
239 bool prev = _thread_monitoring_contention_enabled;
240 _thread_monitoring_contention_enabled = flag;
241
242 return prev;
243 }
244
245 bool ThreadService::set_thread_cpu_time_enabled(bool flag) {
246 MutexLocker m(Management_lock);
247
248 bool prev = _thread_cpu_time_enabled;
249 _thread_cpu_time_enabled = flag;
250
251 return prev;
252 }
253
254 bool ThreadService::set_thread_allocated_memory_enabled(bool flag) {
255 MutexLocker m(Management_lock);
256
257 bool prev = _thread_allocated_memory_enabled;
258 _thread_allocated_memory_enabled = flag;
259
260 return prev;
261 }
262
263 // GC support
264 void ThreadService::oops_do(OopClosure* f) {
265 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
266 dump->oops_do(f);
267 }
268 }
269
270 void ThreadService::metadata_do(void f(Metadata*)) {
271 for (ThreadDumpResult* dump = _threaddump_list; dump != NULL; dump = dump->next()) {
272 dump->metadata_do(f);
273 }
274 }
275
276 void ThreadService::add_thread_dump(ThreadDumpResult* dump) {
277 MutexLocker ml(Management_lock);
278 if (_threaddump_list == NULL) {
279 _threaddump_list = dump;
280 } else {
281 dump->set_next(_threaddump_list);
282 _threaddump_list = dump;
283 }
284 }
285
286 void ThreadService::remove_thread_dump(ThreadDumpResult* dump) {
287 MutexLocker ml(Management_lock);
288
289 ThreadDumpResult* prev = NULL;
290 bool found = false;
291 for (ThreadDumpResult* d = _threaddump_list; d != NULL; prev = d, d = d->next()) {
292 if (d == dump) {
293 if (prev == NULL) {
294 _threaddump_list = dump->next();
295 } else {
296 prev->set_next(dump->next());
297 }
298 found = true;
299 break;
300 }
301 }
302 assert(found, "The threaddump result to be removed must exist.");
303 }
304
305 // Dump stack trace of threads specified in the given threads array.
306 // Returns StackTraceElement[][] each element is the stack trace of a thread in
307 // the corresponding entry in the given threads array
308 Handle ThreadService::dump_stack_traces(GrowableArray<instanceHandle>* threads,
309 int num_threads,
310 TRAPS) {
311 assert(num_threads > 0, "just checking");
312
313 ThreadDumpResult dump_result;
314 VM_ThreadDump op(&dump_result,
315 threads,
316 num_threads,
317 -1, /* entire stack */
318 false, /* with locked monitors */
319 false /* with locked synchronizers */);
320 VMThread::execute(&op);
321
322 // Allocate the resulting StackTraceElement[][] object
323
324 ResourceMark rm(THREAD);
325 Klass* k = SystemDictionary::resolve_or_fail(vmSymbols::java_lang_StackTraceElement_array(), true, CHECK_NH);
326 ObjArrayKlass* ik = ObjArrayKlass::cast(k);
327 objArrayOop r = oopFactory::new_objArray(ik, num_threads, CHECK_NH);
328 objArrayHandle result_obj(THREAD, r);
329
330 int num_snapshots = dump_result.num_snapshots();
331 assert(num_snapshots == num_threads, "Must have num_threads thread snapshots");
332 assert(num_snapshots == 0 || dump_result.t_list_has_been_set(), "ThreadsList must have been set if we have a snapshot");
333 int i = 0;
334 for (ThreadSnapshot* ts = dump_result.snapshots(); ts != NULL; i++, ts = ts->next()) {
335 ThreadStackTrace* stacktrace = ts->get_stack_trace();
336 if (stacktrace == NULL) {
337 // No stack trace
338 result_obj->obj_at_put(i, NULL);
339 } else {
340 // Construct an array of java/lang/StackTraceElement object
341 Handle backtrace_h = stacktrace->allocate_fill_stack_trace_element_array(CHECK_NH);
342 result_obj->obj_at_put(i, backtrace_h());
343 }
344 }
345
346 return result_obj;
347 }
348
349 void ThreadService::reset_contention_count_stat(JavaThread* thread) {
350 ThreadStatistics* stat = thread->get_thread_stat();
351 if (stat != NULL) {
352 stat->reset_count_stat();
353 }
354 }
355
356 void ThreadService::reset_contention_time_stat(JavaThread* thread) {
357 ThreadStatistics* stat = thread->get_thread_stat();
358 if (stat != NULL) {
359 stat->reset_time_stat();
360 }
361 }
362
363 // Find deadlocks involving raw monitors, object monitors and concurrent locks
364 // if concurrent_locks is true.
365 DeadlockCycle* ThreadService::find_deadlocks_at_safepoint(ThreadsList * t_list, bool concurrent_locks) {
366 assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
367
368 // This code was modified from the original Threads::find_deadlocks code.
369 int globalDfn = 0, thisDfn;
370 // This code is called at a safepoint so this ObjectMonitorHandle
371 // is not strictly necessary.
372 ObjectMonitorHandle omh;
373 ObjectMonitor* waitingToLockMonitor = NULL;
374 JvmtiRawMonitor* waitingToLockRawMonitor = NULL;
375 oop waitingToLockBlocker = NULL;
376 bool blocked_on_monitor = false;
377 JavaThread *currentThread, *previousThread;
378 int num_deadlocks = 0;
379
380 // Initialize the depth-first-number for each JavaThread.
381 JavaThreadIterator jti(t_list);
382 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) {
383 jt->set_depth_first_number(-1);
384 }
385
386 DeadlockCycle* deadlocks = NULL;
387 DeadlockCycle* last = NULL;
388 DeadlockCycle* cycle = new DeadlockCycle();
389 for (JavaThread* jt = jti.first(); jt != NULL; jt = jti.next()) {
390 if (jt->depth_first_number() >= 0) {
391 // this thread was already visited
392 continue;
393 }
394
395 thisDfn = globalDfn;
396 jt->set_depth_first_number(globalDfn++);
397 previousThread = jt;
398 currentThread = jt;
399
400 cycle->reset();
401
402 if (waitingToLockMonitor != NULL) {
403 // Done with the current waitingToLockMonitor value so release
404 // the ObjectMonitorHandle manually before we use it again:
405 omh.unset_om_ptr();
406 }
407 // When there is a deadlock, all the monitors involved in the dependency
408 // cycle must be contended and heavyweight. So we only care about the
409 // heavyweight monitor a thread is waiting to lock.
410 waitingToLockMonitor = jt->current_pending_monitor(&omh);
411 // JVM TI raw monitors can also be involved in deadlocks, and we can be
412 // waiting to lock both a raw monitor and ObjectMonitor at the same time.
413 // It isn't clear how to make deadlock detection work correctly if that
414 // happens.
415 waitingToLockRawMonitor = jt->current_pending_raw_monitor();
416
417 if (concurrent_locks) {
418 waitingToLockBlocker = jt->current_park_blocker();
419 }
420
421 while (waitingToLockMonitor != NULL ||
422 waitingToLockRawMonitor != NULL ||
423 waitingToLockBlocker != NULL) {
424 cycle->add_thread(currentThread);
425 // Give preference to the raw monitor
426 if (waitingToLockRawMonitor != NULL) {
427 Thread* owner = waitingToLockRawMonitor->owner();
428 if (owner != NULL && // the raw monitor could be released at any time
429 owner->is_Java_thread()) {
430 // only JavaThreads can be reported here
431 currentThread = (JavaThread*) owner;
432 }
433 } else if (waitingToLockMonitor != NULL) {
434 address currentOwner = (address)waitingToLockMonitor->owner();
435 if (currentOwner != NULL) {
436 currentThread = Threads::owning_thread_from_monitor_owner(t_list,
437 currentOwner);
438 if (currentThread == NULL) {
439 // This function is called at a safepoint so the JavaThread
440 // that owns waitingToLockMonitor should be findable, but
441 // if it is not findable, then the previous currentThread is
442 // blocked permanently. We record this as a deadlock.
443 num_deadlocks++;
444
445 cycle->set_deadlock(true);
446
447 // add this cycle to the deadlocks list
448 if (deadlocks == NULL) {
449 deadlocks = cycle;
450 } else {
451 last->set_next(cycle);
452 }
453 last = cycle;
454 cycle = new DeadlockCycle();
455 break;
456 }
457 }
458 } else {
459 if (concurrent_locks) {
460 if (waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
461 oop threadObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
462 // This JavaThread (if there is one) is protected by the
463 // ThreadsListSetter in VM_FindDeadlocks::doit().
464 currentThread = threadObj != NULL ? java_lang_Thread::thread(threadObj) : NULL;
465 } else {
466 currentThread = NULL;
467 }
468 }
469 }
470
471 if (currentThread == NULL) {
472 // No dependency on another thread
473 break;
474 }
475 if (currentThread->depth_first_number() < 0) {
476 // First visit to this thread
477 currentThread->set_depth_first_number(globalDfn++);
478 } else if (currentThread->depth_first_number() < thisDfn) {
479 // Thread already visited, and not on a (new) cycle
480 break;
481 } else if (currentThread == previousThread) {
482 // Self-loop, ignore
483 break;
484 } else {
485 // We have a (new) cycle
486 num_deadlocks++;
487
488 cycle->set_deadlock(true);
489
490 // add this cycle to the deadlocks list
491 if (deadlocks == NULL) {
492 deadlocks = cycle;
493 } else {
494 last->set_next(cycle);
495 }
496 last = cycle;
497 cycle = new DeadlockCycle();
498 break;
499 }
500 previousThread = currentThread;
501 if (waitingToLockMonitor != NULL) {
502 // Done with the current waitingToLockMonitor value so release
503 // the ObjectMonitorHandle manually before we use it again:
504 omh.unset_om_ptr();
505 }
506 waitingToLockMonitor = (ObjectMonitor*)currentThread->current_pending_monitor(&omh);
507 if (concurrent_locks) {
508 waitingToLockBlocker = currentThread->current_park_blocker();
509 }
510 }
511
512 }
513 delete cycle;
514 return deadlocks;
515 }
516
517 ThreadDumpResult::ThreadDumpResult() : _num_threads(0), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() {
518
519 // Create a new ThreadDumpResult object and append to the list.
520 // If GC happens before this function returns, Method*
521 // in the stack trace will be visited.
522 ThreadService::add_thread_dump(this);
523 }
524
525 ThreadDumpResult::ThreadDumpResult(int num_threads) : _num_threads(num_threads), _num_snapshots(0), _snapshots(NULL), _last(NULL), _next(NULL), _setter() {
526 // Create a new ThreadDumpResult object and append to the list.
527 // If GC happens before this function returns, oops
528 // will be visited.
529 ThreadService::add_thread_dump(this);
530 }
531
532 ThreadDumpResult::~ThreadDumpResult() {
533 ThreadService::remove_thread_dump(this);
534
535 // free all the ThreadSnapshot objects created during
536 // the VM_ThreadDump operation
537 ThreadSnapshot* ts = _snapshots;
538 while (ts != NULL) {
539 ThreadSnapshot* p = ts;
540 ts = ts->next();
541 delete p;
542 }
543 }
544
545 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot() {
546 ThreadSnapshot* ts = new ThreadSnapshot();
547 link_thread_snapshot(ts);
548 return ts;
549 }
550
551 ThreadSnapshot* ThreadDumpResult::add_thread_snapshot(JavaThread* thread) {
552 // Note: it is very important that the ThreadSnapshot* gets linked before
553 // ThreadSnapshot::initialize gets called. This is to ensure that
554 // ThreadSnapshot::oops_do can get called prior to the field
555 // ThreadSnapshot::_threadObj being assigned a value (to prevent a dangling
556 // oop).
557 ThreadSnapshot* ts = new ThreadSnapshot();
558 link_thread_snapshot(ts);
559 ts->initialize(t_list(), thread);
560 return ts;
561 }
562
563 void ThreadDumpResult::link_thread_snapshot(ThreadSnapshot* ts) {
564 assert(_num_threads == 0 || _num_snapshots < _num_threads,
565 "_num_snapshots must be less than _num_threads");
566 _num_snapshots++;
567 if (_snapshots == NULL) {
568 _snapshots = ts;
569 } else {
570 _last->set_next(ts);
571 }
572 _last = ts;
573 }
574
575 void ThreadDumpResult::oops_do(OopClosure* f) {
576 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
577 ts->oops_do(f);
578 }
579 }
580
581 void ThreadDumpResult::metadata_do(void f(Metadata*)) {
582 for (ThreadSnapshot* ts = _snapshots; ts != NULL; ts = ts->next()) {
583 ts->metadata_do(f);
584 }
585 }
586
587 ThreadsList* ThreadDumpResult::t_list() {
588 return _setter.list();
589 }
590
591 StackFrameInfo::StackFrameInfo(javaVFrame* jvf, bool with_lock_info) {
592 _method = jvf->method();
593 _bci = jvf->bci();
594 _class_holder = _method->method_holder()->klass_holder();
595 _locked_monitors = NULL;
596 if (with_lock_info) {
597 ResourceMark rm;
598 GrowableArray<MonitorInfo*>* list = jvf->locked_monitors();
599 int length = list->length();
600 if (length > 0) {
601 _locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(length, true);
602 for (int i = 0; i < length; i++) {
603 MonitorInfo* monitor = list->at(i);
604 assert(monitor->owner() != NULL, "This monitor must have an owning object");
605 _locked_monitors->append(monitor->owner());
606 }
607 }
608 }
609 }
610
611 void StackFrameInfo::oops_do(OopClosure* f) {
612 if (_locked_monitors != NULL) {
613 int length = _locked_monitors->length();
614 for (int i = 0; i < length; i++) {
615 f->do_oop((oop*) _locked_monitors->adr_at(i));
616 }
617 }
618 f->do_oop(&_class_holder);
619 }
620
621 void StackFrameInfo::metadata_do(void f(Metadata*)) {
622 f(_method);
623 }
624
625 void StackFrameInfo::print_on(outputStream* st) const {
626 ResourceMark rm;
627 java_lang_Throwable::print_stack_element(st, method(), bci());
628 int len = (_locked_monitors != NULL ? _locked_monitors->length() : 0);
629 for (int i = 0; i < len; i++) {
630 oop o = _locked_monitors->at(i);
631 st->print_cr("\t- locked <" INTPTR_FORMAT "> (a %s)", p2i(o), o->klass()->external_name());
632 }
633
634 }
635
636 // Iterate through monitor cache to find JNI locked monitors
637 class InflatedMonitorsClosure: public MonitorClosure {
638 private:
639 ThreadStackTrace* _stack_trace;
640 Thread* _thread;
641 public:
642 InflatedMonitorsClosure(Thread* t, ThreadStackTrace* st) {
643 _thread = t;
644 _stack_trace = st;
645 }
646 void do_monitor(ObjectMonitor* mid) {
647 if (mid->owner() == _thread) {
648 oop object = (oop) mid->object();
649 if (!_stack_trace->is_owned_monitor_on_stack(object)) {
650 _stack_trace->add_jni_locked_monitor(object);
651 }
652 }
653 }
654 };
655
656 ThreadStackTrace::ThreadStackTrace(JavaThread* t, bool with_locked_monitors) {
657 _thread = t;
658 _frames = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<StackFrameInfo*>(INITIAL_ARRAY_SIZE, true);
659 _depth = 0;
660 _with_locked_monitors = with_locked_monitors;
661 if (_with_locked_monitors) {
662 _jni_locked_monitors = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true);
663 } else {
664 _jni_locked_monitors = NULL;
665 }
666 }
667
668 ThreadStackTrace::~ThreadStackTrace() {
669 for (int i = 0; i < _frames->length(); i++) {
670 delete _frames->at(i);
671 }
672 delete _frames;
673 if (_jni_locked_monitors != NULL) {
674 delete _jni_locked_monitors;
675 }
676 }
677
678 void ThreadStackTrace::dump_stack_at_safepoint(int maxDepth) {
679 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
680
681 if (_thread->has_last_Java_frame()) {
682 RegisterMap reg_map(_thread);
683 vframe* start_vf = _thread->last_java_vframe(®_map);
684 int count = 0;
685 for (vframe* f = start_vf; f; f = f->sender() ) {
686 if (maxDepth >= 0 && count == maxDepth) {
687 // Skip frames if more than maxDepth
688 break;
689 }
690 if (f->is_java_frame()) {
691 javaVFrame* jvf = javaVFrame::cast(f);
692 add_stack_frame(jvf);
693 count++;
694 } else {
695 // Ignore non-Java frames
696 }
697 }
698 }
699
700 if (_with_locked_monitors) {
701 // Iterate inflated monitors and find monitors locked by this thread
702 // not found in the stack
703 InflatedMonitorsClosure imc(_thread, this);
704 ObjectSynchronizer::monitors_iterate(&imc);
705 }
706 }
707
708
709 bool ThreadStackTrace::is_owned_monitor_on_stack(oop object) {
710 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
711
712 bool found = false;
713 int num_frames = get_stack_depth();
714 for (int depth = 0; depth < num_frames; depth++) {
715 StackFrameInfo* frame = stack_frame_at(depth);
716 int len = frame->num_locked_monitors();
717 GrowableArray<oop>* locked_monitors = frame->locked_monitors();
718 for (int j = 0; j < len; j++) {
719 oop monitor = locked_monitors->at(j);
720 assert(monitor != NULL, "must be a Java object");
721 if (monitor == object) {
722 found = true;
723 break;
724 }
725 }
726 }
727 return found;
728 }
729
730 Handle ThreadStackTrace::allocate_fill_stack_trace_element_array(TRAPS) {
731 InstanceKlass* ik = SystemDictionary::StackTraceElement_klass();
732 assert(ik != NULL, "must be loaded in 1.4+");
733
734 // Allocate an array of java/lang/StackTraceElement object
735 objArrayOop ste = oopFactory::new_objArray(ik, _depth, CHECK_NH);
736 objArrayHandle backtrace(THREAD, ste);
737 for (int j = 0; j < _depth; j++) {
738 StackFrameInfo* frame = _frames->at(j);
739 methodHandle mh(THREAD, frame->method());
740 oop element = java_lang_StackTraceElement::create(mh, frame->bci(), CHECK_NH);
741 backtrace->obj_at_put(j, element);
742 }
743 return backtrace;
744 }
745
746 void ThreadStackTrace::add_stack_frame(javaVFrame* jvf) {
747 StackFrameInfo* frame = new StackFrameInfo(jvf, _with_locked_monitors);
748 _frames->append(frame);
749 _depth++;
750 }
751
752 void ThreadStackTrace::oops_do(OopClosure* f) {
753 int length = _frames->length();
754 for (int i = 0; i < length; i++) {
755 _frames->at(i)->oops_do(f);
756 }
757
758 length = (_jni_locked_monitors != NULL ? _jni_locked_monitors->length() : 0);
759 for (int j = 0; j < length; j++) {
760 f->do_oop((oop*) _jni_locked_monitors->adr_at(j));
761 }
762 }
763
764 void ThreadStackTrace::metadata_do(void f(Metadata*)) {
765 int length = _frames->length();
766 for (int i = 0; i < length; i++) {
767 _frames->at(i)->metadata_do(f);
768 }
769 }
770
771
772 ConcurrentLocksDump::~ConcurrentLocksDump() {
773 if (_retain_map_on_free) {
774 return;
775 }
776
777 for (ThreadConcurrentLocks* t = _map; t != NULL;) {
778 ThreadConcurrentLocks* tcl = t;
779 t = t->next();
780 delete tcl;
781 }
782 }
783
784 void ConcurrentLocksDump::dump_at_safepoint() {
785 // dump all locked concurrent locks
786 assert(SafepointSynchronize::is_at_safepoint(), "all threads are stopped");
787
788 GrowableArray<oop>* aos_objects = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<oop>(INITIAL_ARRAY_SIZE, true /* C_heap */);
789
790 // Find all instances of AbstractOwnableSynchronizer
791 HeapInspection::find_instances_at_safepoint(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass(),
792 aos_objects);
793 // Build a map of thread to its owned AQS locks
794 build_map(aos_objects);
795
796 delete aos_objects;
797 }
798
799
800 // build a map of JavaThread to all its owned AbstractOwnableSynchronizer
801 void ConcurrentLocksDump::build_map(GrowableArray<oop>* aos_objects) {
802 int length = aos_objects->length();
803 for (int i = 0; i < length; i++) {
804 oop o = aos_objects->at(i);
805 oop owner_thread_obj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(o);
806 if (owner_thread_obj != NULL) {
807 // See comments in ThreadConcurrentLocks to see how this
808 // JavaThread* is protected.
809 JavaThread* thread = java_lang_Thread::thread(owner_thread_obj);
810 assert(o->is_instance(), "Must be an instanceOop");
811 add_lock(thread, (instanceOop) o);
812 }
813 }
814 }
815
816 void ConcurrentLocksDump::add_lock(JavaThread* thread, instanceOop o) {
817 ThreadConcurrentLocks* tcl = thread_concurrent_locks(thread);
818 if (tcl != NULL) {
819 tcl->add_lock(o);
820 return;
821 }
822
823 // First owned lock found for this thread
824 tcl = new ThreadConcurrentLocks(thread);
825 tcl->add_lock(o);
826 if (_map == NULL) {
827 _map = tcl;
828 } else {
829 _last->set_next(tcl);
830 }
831 _last = tcl;
832 }
833
834 ThreadConcurrentLocks* ConcurrentLocksDump::thread_concurrent_locks(JavaThread* thread) {
835 for (ThreadConcurrentLocks* tcl = _map; tcl != NULL; tcl = tcl->next()) {
836 if (tcl->java_thread() == thread) {
837 return tcl;
838 }
839 }
840 return NULL;
841 }
842
843 void ConcurrentLocksDump::print_locks_on(JavaThread* t, outputStream* st) {
844 st->print_cr(" Locked ownable synchronizers:");
845 ThreadConcurrentLocks* tcl = thread_concurrent_locks(t);
846 GrowableArray<instanceOop>* locks = (tcl != NULL ? tcl->owned_locks() : NULL);
847 if (locks == NULL || locks->is_empty()) {
848 st->print_cr("\t- None");
849 st->cr();
850 return;
851 }
852
853 for (int i = 0; i < locks->length(); i++) {
854 instanceOop obj = locks->at(i);
855 st->print_cr("\t- <" INTPTR_FORMAT "> (a %s)", p2i(obj), obj->klass()->external_name());
856 }
857 st->cr();
858 }
859
860 ThreadConcurrentLocks::ThreadConcurrentLocks(JavaThread* thread) {
861 _thread = thread;
862 _owned_locks = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<instanceOop>(INITIAL_ARRAY_SIZE, true);
863 _next = NULL;
864 }
865
866 ThreadConcurrentLocks::~ThreadConcurrentLocks() {
867 delete _owned_locks;
868 }
869
870 void ThreadConcurrentLocks::add_lock(instanceOop o) {
871 _owned_locks->append(o);
872 }
873
874 void ThreadConcurrentLocks::oops_do(OopClosure* f) {
875 int length = _owned_locks->length();
876 for (int i = 0; i < length; i++) {
877 f->do_oop((oop*) _owned_locks->adr_at(i));
878 }
879 }
880
881 ThreadStatistics::ThreadStatistics() {
882 _contended_enter_count = 0;
883 _monitor_wait_count = 0;
884 _sleep_count = 0;
885 _count_pending_reset = false;
886 _timer_pending_reset = false;
887 memset((void*) _perf_recursion_counts, 0, sizeof(_perf_recursion_counts));
888 }
889
890 void ThreadSnapshot::initialize(ThreadsList * t_list, JavaThread* thread) {
891 _thread = thread;
892 _threadObj = thread->threadObj();
893
894 ThreadStatistics* stat = thread->get_thread_stat();
895 _contended_enter_ticks = stat->contended_enter_ticks();
896 _contended_enter_count = stat->contended_enter_count();
897 _monitor_wait_ticks = stat->monitor_wait_ticks();
898 _monitor_wait_count = stat->monitor_wait_count();
899 _sleep_ticks = stat->sleep_ticks();
900 _sleep_count = stat->sleep_count();
901
902 _thread_status = java_lang_Thread::get_thread_status(_threadObj);
903 _is_ext_suspended = thread->is_being_ext_suspended();
904 _is_in_native = (thread->thread_state() == _thread_in_native);
905
906 if (_thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER ||
907 _thread_status == java_lang_Thread::IN_OBJECT_WAIT ||
908 _thread_status == java_lang_Thread::IN_OBJECT_WAIT_TIMED) {
909
910 Handle obj = ThreadService::get_current_contended_monitor(thread);
911 if (obj() == NULL) {
912 // monitor no longer exists; thread is not blocked
913 _thread_status = java_lang_Thread::RUNNABLE;
914 } else {
915 _blocker_object = obj();
916 JavaThread* owner = ObjectSynchronizer::get_lock_owner(t_list, obj);
917 if ((owner == NULL && _thread_status == java_lang_Thread::BLOCKED_ON_MONITOR_ENTER)
918 || (owner != NULL && owner->is_attaching_via_jni())) {
919 // ownership information of the monitor is not available
920 // (may no longer be owned or releasing to some other thread)
921 // make this thread in RUNNABLE state.
922 // And when the owner thread is in attaching state, the java thread
923 // is not completely initialized. For example thread name and id
924 // and may not be set, so hide the attaching thread.
925 _thread_status = java_lang_Thread::RUNNABLE;
926 _blocker_object = NULL;
927 } else if (owner != NULL) {
928 _blocker_object_owner = owner->threadObj();
929 }
930 }
931 }
932
933 // Support for JSR-166 locks
934 if (_thread_status == java_lang_Thread::PARKED || _thread_status == java_lang_Thread::PARKED_TIMED) {
935 _blocker_object = thread->current_park_blocker();
936 if (_blocker_object != NULL && _blocker_object->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass())) {
937 _blocker_object_owner = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(_blocker_object);
938 }
939 }
940 }
941
942 ThreadSnapshot::~ThreadSnapshot() {
943 delete _stack_trace;
944 delete _concurrent_locks;
945 }
946
947 void ThreadSnapshot::dump_stack_at_safepoint(int max_depth, bool with_locked_monitors) {
948 _stack_trace = new ThreadStackTrace(_thread, with_locked_monitors);
949 _stack_trace->dump_stack_at_safepoint(max_depth);
950 }
951
952
953 void ThreadSnapshot::oops_do(OopClosure* f) {
954 f->do_oop(&_threadObj);
955 f->do_oop(&_blocker_object);
956 f->do_oop(&_blocker_object_owner);
957 if (_stack_trace != NULL) {
958 _stack_trace->oops_do(f);
959 }
960 if (_concurrent_locks != NULL) {
961 _concurrent_locks->oops_do(f);
962 }
963 }
964
965 void ThreadSnapshot::metadata_do(void f(Metadata*)) {
966 if (_stack_trace != NULL) {
967 _stack_trace->metadata_do(f);
968 }
969 }
970
971
972 DeadlockCycle::DeadlockCycle() {
973 _is_deadlock = false;
974 _threads = new (ResourceObj::C_HEAP, mtInternal) GrowableArray<JavaThread*>(INITIAL_ARRAY_SIZE, true);
975 _next = NULL;
976 }
977
978 DeadlockCycle::~DeadlockCycle() {
979 delete _threads;
980 }
981
982 void DeadlockCycle::print_on_with(ThreadsList * t_list, outputStream* st) const {
983 st->cr();
984 st->print_cr("Found one Java-level deadlock:");
985 st->print("=============================");
986
987 JavaThread* currentThread;
988 JvmtiRawMonitor* waitingToLockRawMonitor;
989 oop waitingToLockBlocker;
990 int len = _threads->length();
991 for (int i = 0; i < len; i++) {
992 currentThread = _threads->at(i);
993 // This code is called at a safepoint so this ObjectMonitorHandle
994 // is not strictly necessary.
995 ObjectMonitorHandle omh;
996 ObjectMonitor* waitingToLockMonitor = currentThread->current_pending_monitor(&omh);
997 waitingToLockRawMonitor = currentThread->current_pending_raw_monitor();
998 waitingToLockBlocker = currentThread->current_park_blocker();
999 st->cr();
1000 st->print_cr("\"%s\":", currentThread->get_thread_name());
1001 const char* owner_desc = ",\n which is held by";
1002
1003 // Note: As the JVM TI "monitor contended enter" event callback is executed after ObjectMonitor
1004 // sets the current pending monitor, it is possible to then see a pending raw monitor as well.
1005 if (waitingToLockRawMonitor != NULL) {
1006 st->print(" waiting to lock JVM TI raw monitor " INTPTR_FORMAT, p2i(waitingToLockRawMonitor));
1007 Thread* owner = waitingToLockRawMonitor->owner();
1008 // Could be NULL as the raw monitor could be released at any time if held by non-JavaThread
1009 if (owner != NULL) {
1010 if (owner->is_Java_thread()) {
1011 currentThread = (JavaThread*) owner;
1012 st->print_cr("%s \"%s\"", owner_desc, currentThread->get_thread_name());
1013 } else {
1014 st->print_cr(",\n which has now been released");
1015 }
1016 } else {
1017 st->print_cr("%s non-Java thread=" PTR_FORMAT, owner_desc, p2i(owner));
1018 }
1019 }
1020
1021 if (waitingToLockMonitor != NULL) {
1022 st->print(" waiting to lock monitor " INTPTR_FORMAT, p2i(waitingToLockMonitor));
1023 oop obj = (oop)waitingToLockMonitor->object();
1024 st->print(" (object " INTPTR_FORMAT ", a %s)", p2i(obj),
1025 obj->klass()->external_name());
1026
1027 if (!currentThread->current_pending_monitor_is_from_java()) {
1028 owner_desc = "\n in JNI, which is held by";
1029 }
1030 currentThread = Threads::owning_thread_from_monitor_owner(t_list,
1031 (address)waitingToLockMonitor->owner());
1032 if (currentThread == NULL) {
1033 // The deadlock was detected at a safepoint so the JavaThread
1034 // that owns waitingToLockMonitor should be findable, but
1035 // if it is not findable, then the previous currentThread is
1036 // blocked permanently.
1037 st->print_cr("%s UNKNOWN_owner_addr=" PTR_FORMAT, owner_desc,
1038 p2i(waitingToLockMonitor->owner()));
1039 continue;
1040 }
1041 } else {
1042 st->print(" waiting for ownable synchronizer " INTPTR_FORMAT ", (a %s)",
1043 p2i(waitingToLockBlocker),
1044 waitingToLockBlocker->klass()->external_name());
1045 assert(waitingToLockBlocker->is_a(SystemDictionary::java_util_concurrent_locks_AbstractOwnableSynchronizer_klass()),
1046 "Must be an AbstractOwnableSynchronizer");
1047 oop ownerObj = java_util_concurrent_locks_AbstractOwnableSynchronizer::get_owner_threadObj(waitingToLockBlocker);
1048 currentThread = java_lang_Thread::thread(ownerObj);
1049 assert(currentThread != NULL, "AbstractOwnableSynchronizer owning thread is unexpectedly NULL");
1050 }
1051 st->print_cr("%s \"%s\"", owner_desc, currentThread->get_thread_name());
1052 }
1053
1054 st->cr();
1055
1056 // Print stack traces
1057 bool oldJavaMonitorsInStackTrace = JavaMonitorsInStackTrace;
1058 JavaMonitorsInStackTrace = true;
1059 st->print_cr("Java stack information for the threads listed above:");
1060 st->print_cr("===================================================");
1061 for (int j = 0; j < len; j++) {
1062 currentThread = _threads->at(j);
1063 st->print_cr("\"%s\":", currentThread->get_thread_name());
1064 currentThread->print_stack_on(st);
1065 }
1066 JavaMonitorsInStackTrace = oldJavaMonitorsInStackTrace;
1067 }
1068
1069 ThreadsListEnumerator::ThreadsListEnumerator(Thread* cur_thread,
1070 bool include_jvmti_agent_threads,
1071 bool include_jni_attaching_threads) {
1072 assert(cur_thread == Thread::current(), "Check current thread");
1073
1074 int init_size = ThreadService::get_live_thread_count();
1075 _threads_array = new GrowableArray<instanceHandle>(init_size);
1076
1077 for (JavaThreadIteratorWithHandle jtiwh; JavaThread *jt = jtiwh.next(); ) {
1078 // skips JavaThreads in the process of exiting
1079 // and also skips VM internal JavaThreads
1080 // Threads in _thread_new or _thread_new_trans state are included.
1081 // i.e. threads have been started but not yet running.
1082 if (jt->threadObj() == NULL ||
1083 jt->is_exiting() ||
1084 !java_lang_Thread::is_alive(jt->threadObj()) ||
1085 jt->is_hidden_from_external_view()) {
1086 continue;
1087 }
1088
1089 // skip agent threads
1090 if (!include_jvmti_agent_threads && jt->is_jvmti_agent_thread()) {
1091 continue;
1092 }
1093
1094 // skip jni threads in the process of attaching
1095 if (!include_jni_attaching_threads && jt->is_attaching_via_jni()) {
1096 continue;
1097 }
1098
1099 instanceHandle h(cur_thread, (instanceOop) jt->threadObj());
1100 _threads_array->append(h);
1101 }
1102 }